Multi-ratio transmission

ABSTRACT

The transmission with nine forward and one reverse gear includes four planetary gearsets, eight shafts and six shifting elements, the sun gear of gearset (P 1 ) couples shaft ( 4 ) which can couple brake ( 04 ) to the housing. The input shaft can couple, via clutch ( 13 ), shaft ( 03 ) which is couples the carrier of gearset (P 1 ) and the ring gear of gearset (P 4 ) and can couple, via brake ( 03 ), the housing. The input shaft can couple, via clutch ( 16 ), shaft ( 6 ) which couples the ring gears of gearsets (P 2 , P 3 ) and can couple, via clutch ( 17 ), shaft ( 7 ) which couples the sun gear of gearset (P 2 ) and the ring gear of gearset (P 1 ). Shaft ( 8 ) couples the carriers of gearsets (P 2 , P 4 ). Shaft ( 5 ) couples the sun gears of gearsets (P 3 , P 4 ) and can couple, via brake ( 05 ), the housing. The output shaft couples the carrier of gearset (P 3 ).

This application is a National Stage completion of PCT/EP2013/050353filed Jan. 10, 2014, which claims priority from German patentapplication serial no. 10 2012 202 812.9 filed Feb. 24, 2012.

FIELD OF THE INVENTION

The present invention concerns a multi-ratio transmission of planetarydesign, in particular an automatic transmission for a motor vehicle.

BACKGROUND OF THE INVENTION

According to the prior art automatic transmissions, in particular formotor vehicles, comprise planetary gearsets which are shifted by meansof frictional or shifting elements such as clutches and brakes, and areusually connected with a starting element which can be operated withslip and is optionally provided with a bridging clutch, such as ahydrodynamic torque converter or a fluid coupling.

Such an automatic transmission is known, for example, from DE 199 12 480B4 by the present applicant. It comprises three single-carrier planetarygearsets as well as three brakes and two clutches for engaging sixforward gears and one reverse gear, a drive input shaft and a driveoutput shaft, wherein the carrier of the first planetary gearset isconnected permanently to the ring gear of the second planetary gearset,the carrier of the second planetary gearset to the ring gear of thethird planetary gearset and the drive input shaft is connected directlyto the sun gear of the second planetary gearset.

Furthermore, in this known transmission it is provided that the driveinput shaft can be connected by the first clutch to the sun gear of thefirst planetary gearset and by the second clutch to the carrier of thefirst planetary gearset, the sun gear of the first planetary gearset canbe connected by the first brake to a housing of the transmission and thecarrier of the first planetary gearset can be connected by the secondbrake to the housing of the transmission, whereas the sun gear of thethird planetary gearset can be connected by the third brake to thehousing of the transmission. The drive output shaft of the transmissionis connected permanently to the carrier of the third planetary gearsetand to the ring gear of the first planetary gearset.

In addition a 9-gear multi-stage transmission is known from DE 29 36 969A1; this comprises eight shifting elements and four planetary gearsets,one planetary gearset serving as the upstream gearset and the maintransmission comprising a Simpson gearset and a further planetarygearset that serves as a reversing gearset.

Other multi-stage transmissions are known, for example, from DE 10 2005010 210 A1 and DE 10 2006 006 637 A1 by the present applicant.

In general, automatically shifted vehicle transmissions of planetarydesign have already been described many times in the prior art and arecontinually undergoing further development and improvement. Thesetransmissions should take up little structural space, in particularrequiring a small number of shifting elements, and in sequentialshifting operations should avoid double shifts, i.e. an engagement ordisengagement of two shifting elements at a time, so that for shiftingoperations in defined gear groups in each case only one shifting elementis changed.

From DE 10 2008 000 428 A1 by the present applicant a multi-stagetransmission of planetary design is known, which comprises a drive inputand a drive output arranged in a housing. In this known transmissionthere are at least four planetary gearsets, denoted in what follows asthe first, second, third and fourth planetary gearsets, at least eightrotating shafts—denoted in what follows as the drive input shaft, thedrive output shaft and the third, fourth, fifth, sixth, seventh andeighth shafts—and at least six shifting elements including brakes andclutches, whose selective engagement produces various gear ratiosbetween the drive input and the drive output, so that preferably nineforward gears and one reverse gear can be produced.

In this case the first and second planetary gearsets, preferablydesigned as minus planetary gearsets, namely ones with a negative fixedtransmission gear ratio, form a shiftable upstream gearset whereas thethird and fourth planetary gearsets form a main gearset.

In this known multi-stage transmission it is provided that the carriersof the first and second planetary gearsets are coupled with one anotherby the fourth shaft, which is connected to an element of the maingearset, the ring gear of the first planetary gearset is coupled to thesun gear of the second planetary gearset by way of the eighth shaft,which can be connected detachably to the drive input shaft by a firstclutch, and the sun gear of the first planetary gearset can be coupledby means of the third shaft, via a first brake, to a housing of thetransmission and can be detachably connected, via a second clutch, tothe drive input shaft, whereas the ring gear of the second planetarygearset can be coupled by means of the fifth shaft, via a second brake,to a housing of the transmission. In addition the seventh shaft ispermanently connected to at least one element of the main gearset andcan be coupled by a third brake to the housing of the transmission,whereas the sixth shaft is permanently connected to at least one furtherelement of the main gearset and can be detachably connected to the driveinput shaft by means of a third clutch; the drive output shaft ispermanently connected to at least one further element of the maingearset.

Preferably, in this known transmission the fourth shaft is permanentlyconnected to the ring gear of the third planetary gearset, whereas thesixth shaft is permanently connected to the ring gear of the fourthplanetary gearset and to the carrier of the third planetary gearset, andcan be detachably connected by the third clutch to the drive inputshaft. Furthermore, the seventh shaft is connected permanently to thesun gears of the third and fourth planetary gearsets and can be coupledby the third brake to a transmission housing. In this case the driveoutput takes place by way of the drive output shaft which is permanentlyconnected to the carrier of the fourth planetary gearset. In addition,the third and fourth planetary gearsets can be combined or reduced to aRavigneaux gearset with a common carrier and a common ring gear.

According to the state of the art the shifting elements of multi-stagetransmissions designed in that way, which are usually in the form ofdisk clutches or disk brakes, are actuated hydraulically, but thisresults disadvantageously in high hydraulic losses. To avoid theseactuation losses, it would be particularly advantageous to use shiftingelements that can be actuated only as required, for exampleelectro-mechanically actuated shifting elements.

To enable the use of shifting elements that can be actuated as required,the shifting elements, clutches in particular, have to be easilyaccessible from outside.

Shifting elements that can be actuated as required are understood tomean, in particular, ones that need energy only for changing theirshifting condition.

Shifting elements that can be actuated as required are also understoodto include ones which require very little or no energy to maintain theirshifting condition. Such shifting elements that can be actuated asrequired can be electro-mechanically and/or electro-hydraulicallyactuated shifting elements.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a multi-stagetransmission of the type mentioned to begin with, comprising nineforward gears and one reverse gear having appropriate gear ratios,wherein the structural complexity, component loading and overall sizeare optimized, and in addition the efficiency in terms of drag lossesand gearing losses is improved. Furthermore the shifting elements of thetransmission should be easily accessible from outside, whereby thefitting of shifting elements that can be actuated as required isfacilitated. Moreover, the transmission should be suitable for bothstandard and also front-transverse mounting designs.

Accordingly, a multi-stage transmission of planetary design according tothe invention is proposed, which comprises a drive input and a driveoutput arranged in a housing. Furthermore, it comprises at least fourplanetary gearsets, called the first, second, third and fourth planetarygearsets in what follows, eight rotating shafts—called the drive inputshaft, the drive output shaft and the third, fourth, fifth, sixth,seventh and eighth shafts in what follows—and six shifting elements,preferably in the form of disk shifting elements or interlockingshifting elements, including brakes and clutches, whose selectiveengagement produces various gear ratios between the drive input and thedrive output, such that preferably nine forward gears and one reversegear can be obtained.

The planetary gearsets of the transmission are preferably designed asminus planetary gearsets.

As is known, a simple minus planetary gearset has a sun gear, a ringgear and a carrier on which planetary gearwheels are mounted to rotate,each of the planetary gearwheels meshes with the sun gear and the ringgear. Thus, if the carrier is held fixed, the ring gear rotates in theopposite direction to the sun gear. In contrast a simple plus planetarygearset has a sun gear, a ring gear and a carrier on which inner andouter planetary gearwheels are mounted to rotate, such that all theinner planetary gearwheels mesh with the sun gear and all the outerplanetary gearwheels mesh with the ring gear and each inner planetarygearwheel meshes with a respective outer planetary gearwheel.Accordingly, if the carrier is held fixed, the ring gear rotates in thesame direction as the sun gear and the fixed transmission gear ratio ispositive.

In a preferred embodiment of the invention the sun gear of the firstplanetary gearset is connected to the fourth shaft, which can be coupledby a second brake to the housing of the transmission, whereas the driveinput shaft can be detachably connected by a first clutch to the thirdshaft, which is connected to the carrier of the first planetary gearsetand to the ring gear of the fourth planetary gearset and which can becoupled by a first brake to the housing of the transmission. Furthermorethe drive input shaft can be detachably connected by a second clutch tothe sixth shaft, which is connected to the ring gear of the secondplanetary gearset and to the ring gear of the third planetary gearset,whereas the drive input shaft can be detachably connected by a thirdclutch to the seventh shaft, which is connected to the sun gear of thesecond planetary gearset and to the ring gear of the first planetarygearset.

In addition the eighth shaft of the transmission is connected to thecarrier of the second planetary gearset and to the carrier of the fourthplanetary gearset, whereas the fifth shaft is connected to the sun gearof the third planetary gearset and to the sun gear of the fourthplanetary gearset and can be coupled by a third brake to the housing,and whereas the drive output shaft of the transmission is connected tothe carrier of the third planetary gearset.

In that the first, second and third clutches are arranged on the driveinput shaft and the other shifting elements are in the form of brakes,easy accessibility of all the shifting elements of the transmission isensured, so that the shifting elements can be designed as shiftingelements that can be actuated as required.

In a further embodiment of the invention, starting from the exampleembodiment just described, the second brake is replaced by a fourthclutch, whereby the sun gear of the first planetary gearset is coupledto the housing of the transmission and the fourth shaft is connected tothe ring gear of the first planetary gearset. In this case the fourthclutch detachably connects the seventh shaft, which is connected to thesun gear of the second planetary gearset, to the fourth shaft, which isconnected to the ring gear of the first planetary gearset.

The design of the multi-stage transmission in accordance with theinvention ensures that the shifting elements of the transmission areeasily accessible, so that the shifting elements can be designed in theform of shifting elements that can be actuated as required. Moreover,particularly for passenger cars suitable gear ratios are available andthe multi-stage transmission has a high overall spread, which improvesdriving comfort and reduces fuel consumption significantly.

Furthermore, since the multi-stage transmission according to theinvention has a small number of shifting elements its structuralcomplexity is reduced considerably. Advantageously, with the multi-stagetransmission according to the invention starting can be carried out bymeans of a hydrodynamic converter, an external starting clutch or evenwith other suitable external starting elements. It is also conceivableto enable a starting process with a starting element integrated in thetransmission. Preferably, a starting element which is actuated in thefirst forward gear and the reverse gear is suitable.

Moreover, the efficiency of the multi-stage transmission in the maindriving gears is good in relation to drag and gearing losses.

Advantageously, the torques imposed on the shifting elements andplanetary gearsets of the multi-stage transmission are small, so thatwear in the multi-stage transmission is advantageously reduced.Furthermore, since the torques are small the dimensions of thetransmission components can be made smaller, whereby the fitting spaceand the corresponding costs can be reduced. Moreover the shafts,shifting elements and planetary gearsets also rotate at low speeds.

Besides, the transmission according to the invention is designed in suchmanner as to enable adaptation to various drive-train designs, in termsof both force flow direction and also spatial considerations.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, an example of the invention will be explained in greater detailwith reference to the attached figures, which show:

FIG. 1: A schematic representation of a first preferred embodiment of amulti stage transmission according to the invention;

FIG. 2: An example shifting scheme for a multi-stage transmission as inFIG. 1;

FIG. 3: A schematic representation of a second preferred embodiment of amulti-stage transmission according to the invention; and

FIG. 4: An example of a shifting scheme for a multi-stage transmissionas in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a multi-stage transmission according to the inventionhaving a drive input shaft 1, a drive output shaft 2 and four planetarygearsets P1, P2, P3 and P4, which are arranged in a housing G. In theexample shown in FIG. 1 the planetary gearsets P1, P2, P3 and P4 aredesigned as minus planetary gearsets. According to the invention, atleast one of the planetary gearsets P1, P2, P3, P4 can be a plusplanetary gearset if at the same time the carrier and ring gearconnection is exchanged and, compared with the minus planetary gearsetdesign, the value of the fixed transmission ratio is increased by 1.

In the example embodiment shown, as viewed axially P1, P2, P3 P4 arearranged in the sequence P1 (first planetary gearset), P2 (secondplanetary gearset), P3 (third planetary gearset and P4 (fourth planetarygearset). According to the invention, the axial sequence of theindividual planetary gearsets and the arrangement of the shiftingelements can be chosen freely so long as it enables the elements to beconnected appropriately.

As can be seen from FIG. 1, six shifting elements are provided, namelythree brakes 03, 04, 05 and three clutches 13, 16, 17. The spatialarrangement of the shifting elements can be as desired and is onlyrestricted by their dimensions and the overall outer shape. The clutchesand brakes of the transmission are preferably in the form of frictionalor disk shifting elements, although they can also be interlockingshifting elements.

With these shifting elements a selective engagement of nine forwardgears and one reverse gear can be obtained. The multi-stage transmissionaccording to the invention has a total of eight rotating shafts, namely1, 2, 3, 4, 5, 6, 7 and 8, of which the drive input shaft is the firstshaft 1 and the drive output shaft is the second shaft 2 of thetransmission.

According to the invention, in the multi-stage transmission of FIG. 1 itis provided that the sun gear of the first planetary gearset P1 isconnected to the fourth shaft 4, which can be coupled by a second brake04 to the transmission housing G, whereas the drive input shaft 1 can bedetachably connected by a first clutch 13 to the third shaft 3, which isconnected to the carrier of the first planetary gearset P1 and to thering gear of the fourth planetary gearset P4 and which can be coupled bya first brake 03 to the transmission housing G. The drive input shaft 1can be detachably connected by a second clutch 16 to the sixth shaft 6,which is connected to the ring gear of the second planetary gearset P2and to the ring gear of the third planetary gearset P3, and which can bedetachably connected by a third clutch 17 to the seventh shaft 7, whichis connected to the sun gear of the second planetary gearset P2 and tothe ring gear of the first planetary gearset P1.

According to the invention, the eighth shaft 8 of the transmission isconnected to the carrier of the second planetary gearset P2 and to thecarrier of the fourth planetary gearset P4, whereas the fifth shaft 5 isconnected to the sun gear of the third planetary gearset P3 and to thesun gear of the fourth planetary gearset P4 and can be coupled by athird brake 05 to the housing; the drive output shaft 2 of thetransmission is connected to the carrier of the third planetary gearsetP3.

In the example embodiment shown, the third brake 05 in particular issuitable to be designed as a claw shifting element, whereby fuelconsumption is significantly improved.

FIG. 2 shows an example shifting scheme for a multi-stage transmissionas in FIG. 1. For each gear three shifting element are closed. Theshifting scheme shows the respective transmission ratios i of theindividual gear steps and the gear intervals or step intervals φ to thenext-higher gear determined therefrom, the value of the transmission'sspread being 9.009 overall.

The values for the fixed transmission ratios of the planetary gearsetsP1, P2, P3, P4 designed as minus planetary gearsets in the example shownare −1.790, −2.588, −2.584 and −3.900 respectively. FIG. 2 shows that ina sequential shift pattern, in each case only one shifting element hasto be engaged and one shifting element disengaged, since two adjacentgears use two shifting elements together. It can also be seen that alarge spread with small gear intervals is achieved.

The first forward gear is obtained by closing the second and thirdbrakes 04, 05 and the third clutch 17, the second forward gear byclosing the second and third brakes and the first clutch 13, the thirdforward gear by closing the third brake 05 and the first and thirdclutches 13, 17, the fourth forward gear by closing the third brake 05and the first and second clutches 13, 16, the fifth forward gear, whichin the example shown is designed to be a direct gear, is obtained byclosing the first, second and third clutches, the sixth forward gear byclosing the second brake 04 and the first and second clutches 13, 16,the seventh forward gear by closing the second brake 04 and the secondand third clutches 16, 17, the eighth forward gear by closing the firstand second brakes 03, 04 and the second clutch 16, and the ninth forwardgear by closing the first brake 03 and the second and third clutches 16,17, whereas the reverse gear is obtained by closing the first and thirdbrakes 03, 05 and the third clutch 17.

Alternatively the fourth forward gear can be engaged by other shiftcombinations, which are indicated as M in FIG. 2. Thus, the fourthforward gear can be obtained by closing the second and third brakes 04,05 and the second clutch 16, or by closing the first and third brakes03, 05 and the second clutch 16, or by closing the third brake 05 andthe second and third clutches 16, 17.

Since the third brake 05 and the third clutch 17 are closed in both thefirst forward gear and the reverse gear, these shifting elements can beused as starting elements.

According to the invention, with the same transmission scheme anddepending on the fixed transmission ratio and/or the shifting logic,different gear intervals can also be obtained so thatapplication-specific or vehicle-specific variation is possible.

The example embodiment shown in FIG. 3 corresponds to the embodimentaccording to FIG. 1, with the differences that the second brake 04 isomitted and is replaced by a fourth clutch 47, the sun gear of the firstplanetary gearset P1 is coupled to the transmission housing G and thefourth shaft 4 is connected to the ring gear of the first planetarygearset P1. The fourth clutch 47 detachably connects the seventh shaft7, which is connected to the sun gear of the second planetary gearsetP2, to the fourth shaft 4, which is connected to the ring gear of thefirst planetary gearset P1.

In the transmission shown in FIG. 3 the drive input shaft 1 can bedetachably connected by a first clutch 13 to the third shaft 3, which isconnected to the carrier of the first planetary gearset P1 and to thering gear of the fourth planetary gearset P4, and which can be coupledby a first brake 03 to the transmission housing G, whereas by means of asecond clutch 16 the drive input shaft 1 can be detachably connected tothe sixth shaft 6 which is connected to the ring gear of the secondplanetary gearset P2 and to the ring gear of the third planetary gearsetP3, and by a third clutch 17 to the seventh shaft 7 which is connectedto the sun gear of the second planetary gearset P2 and which can bedetachably connected by the fourth clutch 47 to the fourth shaft 4 whichis connected to the ring gear of the first planetary gearset P1.Furthermore, the eighth shaft 8 is connected to the carrier of thesecond planetary gearset P2 and to the carrier of the fourth planetarygearset P4, whereas the fifth shaft 5 is connected to the sun gear ofthe third planetary gearset P3 and to the sun gear of the fourthplanetary gearset P4, and can be coupled to the housing by a third brake05; the drive output shaft 2 of the transmission is connected to thecarrier of the third planetary gearset P3. The sun gear of the firstplanetary gearset P1 is coupled to the housing G (shaft 0).

Analogously to the example embodiment shown in FIG. 1, as viewed axiallythe first, second and third clutches 13, 16, 17 are preferably arrangednext to one another and can be in the form of disk shifting elementswith a common outer disk carrier.

The object of FIG. 4 is an example shifting scheme for a multi-stagetransmission according to FIG. 3. In the example shown the values forthe fixed transmission ratios of the planetary gearsets P1, P2, P3, P4designed as minus planetary gearsets are −1.790, −2.588, −2.584 and−3.900 respectively.

The first forward gear is obtained by closing the third brake 05 and thethird and fourth clutches 17, 47, the second forward gear by closing thethird brake 05 and the first and fourth clutches 13, 47, the thirdforward gear by closing the third brake 05 and the first and thirdclutches 13, 17, the fourth forward gear by closing the third brake 05and the first and second clutches 13, 16, the fifth forward gear, whichis designed to be a direct gear, by closing the first, second and thirdclutches 13, 16, 17, the sixth forward gear by closing the first, secondand fourth clutches 13, 16, 47, the seventh forward gear by closing thesecond, third and fourth clutches 16, 17, 47, the eighth forward gear byclosing the first brake 03 and the second and fourth clutches 16, 47,while the ninth forward gear is obtained by closing the first brake 03and the second and third clutches 16, 17, whereas the reverse gear isobtained by closing the first and third brakes 03, 05 and the thirdclutch 17.

According to the invention, the fourth forward gear can be engaged byother shift combinations, which are indicated as M in FIG. 4. Thus, thefourth forward gear can be obtained by closing the first and thirdbrakes 03, 05 and the second clutch 16, or by closing the third brake 05and the second and fourth clutches 16, 47, or by closing the third brake5 and the second and third clutches 16, 17.

According to the invention, it is also optionally possible to provideadditional freewheels at any suitable point in the multi-stagetransmission, for example between a shaft and the housing or to connecttwo shafts when necessary.

On the drive input side or on the drive output side an axle differentialand/or a transfer box differential can be arranged.

In an advantageous further development of the invention the drive inputshaft 1 can if necessary be separated from a drive engine by a clutchelement, wherein for the said clutch element a hydrodynamic converter, ahydraulic clutch, a dry starting clutch, a wet starting clutch, amagnetic power clutch or a centrifugal force clutch can be used. It isalso possible to arrange such a starting element behind the transmissionin the force flow direction, and in that case the drive input shaft 1 isconnected permanently to the crankshaft of the drive engine.

The multi-stage transmission according to the invention also enables atorsion oscillation damper to be arranged between the drive engine andthe transmission.

In a further embodiment of the invention (not illustrated), it ispossible to arrange on any shaft, preferably on the drive input shaft 1or the drive output shaft 2, a wear-free brake such as a hydraulic orelectric retarder or the like, this being particularly appropriate foruse in commercial vehicles. Furthermore, a power-take-off drive can beprovided on any shaft, preferably on the drive input shaft 1 or thedrive output shaft 2, for driving additional aggregates.

The frictional shifting elements used can be in the form of powershiftclutches or brakes. In particular, friction-locking clutches or brakessuch as disk clutches, band brakes and/or cone clutches can be used.

A further advantage of the multi-stage transmission proposed herein isthat an electric machine can be connected to any shaft as a generatorand/or as an additional drive machine.

INDEXES

-   0 Shaft-   1 First shaft, drive input shaft-   2 Second shaft, drive output shaft-   3 Third shaft-   4 Fourth shaft-   5 Fifth shaft-   6 Sixth shaft-   7 Seventh shaft-   8 Eighth shaft-   03 First brake-   04 Second brake-   05 Third brake-   13 First clutch-   16 Second clutch-   17 Third clutch-   47 Fourth clutch-   G Housing-   P1 First planetary gearset-   P2 Second planetary gearset-   P3 Third planetary gearset-   P4 Fourth planetary gearset-   i Transmission ratio-   φ Gear interval

The invention claimed is:
 1. A multi-stage automatic transmission of aplanetary design for a motor vehicle, the transmission comprising: adrive input shaft (1) and a drive output shaft (2); first, second, thirdand fourth planetary gearsets (P1, P2, P3, P4) being arranged within ahousing (G), each of the first planetary gearset (P1), the secondplanetary gearset (P2), the third planetary gearset (P3) and the fourthplanetary gearset (P4) comprises a sun gear, a ring gear and a carrier;third, fourth, fifth, sixth, seventh and eighth rotating shafts (3, 4,5, 6, 7, 8); six shifting elements (03, 04, 05, 13, 16, 17) comprisingfirst, second and third brakes (03, 04, 05) and first, second and thirdclutches (13, 16, 17), selective engagement of the first brake, thesecond brake, the third brake, the first clutch, the second clutch andthe third clutch produces various transmission ratios between the driveinput shaft (1) and the drive output shaft (2) such that nine forwardgears and one reverse gear can be implemented; the sun gear of the firstplanetary gearset (P1) is connected to the fourth shaft (4) which isconnectable by the second brake (04) to the housing (G) of thetransmission; the drive input shaft (1) is detachably connectable by thefirst clutch (13) to the third shaft (3) which is connected to thecarrier of the first planetary gearset (P1) and to the ring gear of thefourth planetary gearset (P4), and the third shaft (3) beingconnectable, by the first brake (03), to the housing (G) of thetransmission; the drive input shaft (1) being detachably connected bythe second clutch (16) to the sixth shaft (6) which is connected to thering gear of the second planetary gearset (P2) and to the ring gear ofthe third planetary gearset (P3), the drive input shaft (1) beingdetachably connectable by the third clutch (17) to the seventh shaft (7)which is connected to the sun gear of the second planetary gearset (P2)and to the ring gear of the first planetary gearset (P1); the eighthshaft (8) being connected to the carrier of the second planetary gearset(P2) and to the carrier of the fourth planetary gearset (P4); the fifthshaft (5) being connected to the sun gear of the third planetary gearset(P3) and to the sun gear of the fourth planetary gearset (P4) and beingconnectable by a third brake (05) to the housing (C); and the driveoutput shaft (2) of the transmission is connected to the carrier of thethird planetary gearset (P3).
 2. The multi-stage transmission accordingto claim 1, wherein the first, the second, the third and the fourthplanetary gearsets (P1, P2, P3, P4) are designed as minus planetarygearsets.
 3. The multi-stage transmission according to claim 1, whereinthe first, the second, the third and the fourth planetary gearsets, whenviewed axially, are arranged in a sequence of the first planetarygearset (P1), the second planetary gearset (P2), the third planetarygearset (P3) and the fourth planetary gearset (P4).
 4. The multi-stagetransmission according to claim 1, wherein the six shifting elements(03, 04, 05, 13, 16, 17) of the transmission are designed as shiftingelements that are independently actuatable.
 5. The multi-stagetransmission according to claim 1, wherein the third brake (05) is aninterlocking shifting element.
 6. The multi-stage transmission accordingto claim 1, wherein a first forward gear is implemented by engagement ofthe second and the third brakes (04, 05) and the third clutch (17), asecond forward gear is implemented by engagement of the second and thethird brakes (04, 05) and the first clutch (13), a third forward gear isimplemented by engagement of the third brake (05) and the first and thethird clutches (13, 17), a fourth forward gear is implemented byengagement of the third brake (05), the second clutch (16) and one ofthe first brake (03), the second brake (04), the first clutch (13) andthe third clutch (17), a fifth forward gear is implemented by engagementof the first, the second and the third clutches (13, 16, 17), a sixthforward gear is implemented by engagement of the second brake (04) andthe first and the second clutches (13, 16), a seventh forward gear isimplemented by engagement of the second brake (04) and the second andthe third clutches (16, 17), an eighth forward gear is implemented byengagement of the first and the second brakes (03, 04) and the secondclutch (16), a ninth forward gear is implemented by engagement of thefirst brake (03) and the second and the third clutches (16, 17), and thereverse gear is implemented by engagement of the first and the thirdbrakes (03, 05) and the third clutch (17).
 7. The multi-stagetransmission according to claim 6, wherein the fourth forward gear isimplemented by engagement of the third brake (05), the second clutch(16) and the first brake (03).
 8. The multi-stage transmission accordingto claim 6, wherein the fourth forward gear is implemented by engagementof the third brake (05), the second clutch (16) and the second brake(04).
 9. The multi-stage transmission according to claim 6, wherein thefourth forward gear is implemented by engagement of the third brake(05), the second clutch (16) and the first clutch (13).
 10. Themulti-stage transmission according to claim 6, wherein the fourthforward gear is implemented by engagement of the third brake (05), thesecond clutch (16) and the third clutch (17).
 11. The multi-stagetransmission according to claim 1, wherein the sun gear of the firstplanetary gearset (P1) is connected to the housing (C) and the ring gearof the first planetary gearset (P1) is connectable, by at least one ofthe shifting elements, to the seventh shaft by which the sun gear of thesecond planetary gearset (P2) is connectable to the drive input shaft.12. A multi-stage automatic transmission of planetary design for a motorvehicle, the transmission comprising: a drive input shaft (1) and adrive output shaft (2); first, second, third and fourth planetarygearsets (P1, P2, P3, P4) being arranged within a housing (G), each ofthe first planetary gearset (P1), the second planetary gearset (P2), thethird planetary gearset (P3) and the fourth planetary gearset (P4)comprises a sun gear, a ring gear and a carrier; third, fourth, fifth,sixth, seventh and eighth rotating shafts (3, 4, 5, 6, 7, 8); sixshifting elements (03, 04, 05, 13, 16, 17) comprising first, second andthird brakes (03, 04, 05) and first, second and third clutches (13, 16,17), selective engagement of the first brake, the second brake, thethird brake, the first clutch, the second clutch and the third clutchproduces various transmission ratios between the drive input shaft (1)and the drive output shaft (2) such that nine forward gears and onereverse gear can be implemented; the drive input shaft (1) beingconnectable, via the first clutch (13), to the third shaft (3) and, viathe second clutch (16), to the sixth shaft (6) and, via the third clutch(17), to the seventh shaft (7); the drive output shaft (2) of thetransmission being continuously connected to the carrier of the thirdplanetary gearset (P3); the third shaft (3) being continuously connectedto the carrier of the first planetary gearset (P1) and the ring gear ofthe fourth planetary gearset (P4) and the third shaft (3) beingconnectable, via the first brake (03), to the housing (G) of thetransmission; the fourth shaft (4) being continuously connected to thesun gear of the first planetary gearset (P1) and the fourth shaft (4)being connectable, via the second brake, to the housing (G) of thetransmission; the fifth shaft (5) being continuously connected to thesun gear of the third planetary gearset (P3) and the sun gear of thefourth planetary gearset (P4) and the fifth shaft (5) being connectable,via the third brake (05); to the housing (G); the sixth shaft (6) beingcontinuously connected to the ring gear of the second planetary gearset(P2) and the ring gear of the third planetary gearset (P3), the seventhshaft (7) being continuously connected to the sun gear of the secondplanetary gearset (P2) and the ring gear of the first planetary gearset(P1); and the eighth shaft (8) being continuously connected to thecarrier of the second planetary gearset (P2) and the carrier of thefourth planetary gearset (P4).
 13. The multi-stage transmissionaccording to claim 12, wherein the first, the second, the third and thefourth planetary gearsets (P1, P2, P3, P4) are designed as minusplanetary gearsets.
 14. The multi-stage transmission according to claim12, wherein the first, the second, the third and the fourth planetarygearsets, when viewed axially, are arranged in a sequence of the firstplanetary gearset (P1), the second planetary gearset (P2), the thirdplanetary gearset (P3) and the fourth planetary gearset (P4).
 15. Themulti-stage transmission according to claim 12, wherein the third brake(05) is an interlocking shifting element.
 16. The multi-stagetransmission according to claim 12, wherein a first forward gear isimplemented by engagement of the second and the third brakes (04, 05)and the third clutch (17), a second forward gear is implemented byengagement of the second and the third brakes (04, 05) and the firstclutch (13), a third forward gear is implemented by engagement of thethird brake (05) and the first and the third clutches (13, 17), a fourthforward gear is implemented by engagement of the third brake (05), thesecond clutch (16) and one of the first brake (03), the second brake(04), the first clutch (13) and the third clutch (17), a fifth forwardgear is implemented by engagement of the first, the second and the thirdclutches (13, 16, 17), a sixth forward gear is implemented by engagementof the second brake (04) and the first and the second clutches (13, 16),a seventh forward gear is implemented by engagement of the second brake(04) and the second and the third clutches (16, 17), an eighth forwardgear is implemented by engagement of the first and the second brakes(03, 04) and the second clutch (16), a ninth forward gear is implementedby engagement of the first brake (03) and the second and the thirdclutches (16, 17), and the reverse gear is implemented by engagement ofthe first and the third brakes (03, 05) and the third clutch (17). 17.The multi-stage transmission according to claim 16, wherein the fourthforward gear is implemented by engagement of the third brake (05), thesecond clutch (16) and the first brake (03).
 18. The multi-stagetransmission according to claim 16, wherein the fourth forward gear isimplemented by engagement of the third brake (05), the second clutch(16) and the second brake (04).
 19. The multi-stage transmissionaccording to claim 16, wherein the fourth forward gear is implemented byengagement of the third brake (05), the second clutch (16) and the firstclutch (13).
 20. The multi-stage transmission according to claim 16,wherein the fourth forward gear is implemented by engagement of thethird brake (05), the second clutch (16) and the third clutch (17).